An unprecedented show of support for Israel has come from a group of almost entirely non-Jewish European and American politicians, statesmen and women and theologians.

Led by former Spanish prime minister José Maria Aznar, they have formed the Friends of Israel Initiative, to oppose the rising tide of criticism and delegitimisation that has questioned Israel's right to exist and act in self-defence.

The FII launched its British branch in the House of Commons on Monday, hosted by the new Tory MP Robert Halfon. A standing-room only audience of 300 people was given a grim warning by Mr Aznar: "If Israel goes down, we all go down."

He said halting the process of eroding Israel's rights was "not only important, but vital: to Israel, of course, but to all Western countries".

Fellow founders include former American permanent UN representative John Bolton, former Peruvian president Alejandro Toledo, former Italian Senate president Marcello Pera, fellow Italian politician and journalist Fiamma Nirenstein and British historian Andrew Roberts.

FII has been funded by a dozen private donors from Spain, America, Israel, France, Italy and Britain. It has a working budget of almost £1 million a year. It was launched globally in Paris at the end of May. The next launch will be in Washington in September, followed by Rome and then another event in Paris. Its headquarters is in Madrid.

FII director Rafael Bardaji, who was Mr Aznar's national security adviser, said: "We have been talking about this for months, since Benjamin Netanyahu was elected. People encouraged us to do something, so we put together this non-Jewish group to stand up for Israel, its right to exist and its right to defend itself."

The FII has already commissioned its first paper, by Israel's former UN ambassador Dr Dore Gold, on "The Challenge to Israel's Legitimacy", with a second planned soon. The papers will be circulated among members and put on the FII website.

The largely centre-right group is considering visiting Arab countries in the coming year as well as addressing the United Nations and the European Parliament. There has already been contact with Egypt and the United Arab Emirates. The reach will then be widened to include entertainment - a possible visit to Hollywood - science, and other areas beyond politics. Thousands of people have already signed in support on the FII website.

Mr Bardaji said the FII would not be a rapid reaction force in crises involving Israel except in extreme circumstances.

"We want to open a space for reasonable debate and discussion about Israel's problems, to see that it is treated as any normal democracy with all its pitfalls, to try to remove this automatic discrimination. Then we can engage more serious questions," he said.

The initiative has been broadly welcomed by Israel and Anglo-Jewry's communal groups.

Israel's minister of information, Yuli Edelstein, said: "Someone once said that European antisemitism's ultimate goal was to clean the soul of Europe of its Jews. Right now, this anti-Israel and anti-Zionism approach is expanding to try to clean the Middle East of the presence of the Jewish state. This kind of initiative by prominent European leaders is very important to try to explain that Israel is a normal democracy."

Jon Benjamin, chief executive of the Board of Deputies, said: "Regrettably, the delegitimisation of Israel has become a thriving global phenomenon - ill-informed and prejudicial. It is with optimism therefore that we welcome the new, innovative international Friends of Israel Initiative, which brings a valuable dimension to the enormous task of fighting Israel's right to security and peace."

Zionist Federation chief executive Alan Aziz said: "It's a breath of fresh air. Israel is in the middle of a global battle and needs friends from wherever it can get them. If individuals of this calibre are willing to stand up for Israel, it's an incredibly positive move.

"These people can take the debate about Israel into circles into which the Jewish community is sometimes unable to go."

Doug Krikler, chief executive of UJIA, said: "People have recognised for some time that much of the attack on Israel has been unjustified or out of context and it's encouraging that significant world leaders have taken the decision to present a counter position.

"What is critical is that there is an awareness of the challenges Israel faces. Initiatives such as this will provide a much-needed voice. In what has been a vacuum filled by enemies of Israel."

At Monday's launch, Marcello Perla, former president of the Italian Senate, said that Israel was viewed as the father of human rights. "If that is put in jeopardy, our liberal democratic regime is in jeopardy as well. That's why attacking Israel is attacking the culture of human rights."